Objective: Systemic lupus erythematosus (SLE), an autoimmune condition with diverse clinical manifestations, is reported to have different expression in populations of different ancestry. Most previous studies compared patients of different ethnic groups from geographically distinct cohorts. In our study, we aimed to characterize disease manifestations in patients of different ethnic groups from a single centre, and studied patterns of disease activity over time.
Methods: Demographics, baseline disease characteristics and autoantibody profiles, and disease activity (SLEDAI) measured at each visit, were captured from all consenting patients prospectively followed between 2007 and 2011 in an urban teaching hospital lupus clinic. Ethnicity was self-reported.
Results: Asian ethnicity was significantly associated with more clinically severe SLE. Time-adjusted mean SLEDAI (p = 0.01) and maximum SLEDAI (p = 0.0018) were significantly higher in Asian patients. Asians were more likely to have renal disease (OR 2.9, 95% CI 1.4-5.98; p = 0.004) and persistently active disease (PAD) (OR 2.14, 95% CI 1.05-4.38, p = 0.04). Asian lupus patients also had a significantly higher proportion of autoantibody positivity to anti-dsDNA, anti-RNP, anti-Sm, anti-Ro and anti-La, as well as increased likelihood of hypocomplementaemia and immunosuppressant use.
Conclusion: In this single-cohort study, Asian ethnicity was found to be associated with increased SLE disease activity. This suggests significant inter-ethnic genetic contributions to the regulation of autoimmune responses and disease severity in SLE.
Keywords: Systemic lupus erythematosus; anti-DNA antibodies; renal lupus.